[[I overcontributed $2000 to my 403B in 1997. I've already done my taxes for 1997. What is the penalty if I do nothing? I work Per Diem and it's difficult to guess what my income will be thus increase risk of error. I made $34,761 and I contributed $9336 to my 403B.]]

Well, I don't know if you are overwithheld or not. If your plan administrator didn't tell you, you may not be. Generally, your contributions are 20% of your earned income times your years of service, minus tax free contributions made in prior years...to a max of $9,500.

So check with your plan administrator. If you find that you really ARE overwhthheld, the administrator will refund the overpayment. You'll pay tax (but not penalties) on the refund and earnings in the year that you receive them.